Friday, March 7, 2008

Roundabouts

How popular are roundabouts as solutions in your respective communities? Are they viewed as a panacea (the solution to every traffic problem) or a deathtrap (drivers will never adjust)? Something in between?

3 comments:

I don't think that they are on either extreme end of the spectrum. However, people are fearful of the new and we haven't built any here, though they are constantly being recomended. My question is how do other places model them?

They are rare in these parts - and most people have an opinion about them: good and bad, neither well-informed. (In fact I get tired of people asking why we're not recommending more in high-volume and/or high-speed areas.) But we are considering a few more as part of some intersection treatments - bowtie and median u-turn intersections, for example.

As for modeling, my consultants recommended using VISSIM on a local scale.

Roundabouts were very popular in Maryland with our state's Department of Transportation (MDOT) -- I retired in 2005 and moved from Baltimore to PA. I found them in suburban/rural areas at intersections where traffic needed to be managed but where traffic signals were not necessarily the best way to do that. There is also the famous "Towson Roundabout" which you may have heard about at conferences or in literature. This one is part of a town center where 5+ streets meet and there is active pedestrian traffic. There's been debate about the engineering of its design and adjustments made to the car stop lines (1 space in front of a ped crosswalk) that seem to have helped. This one gets lots of use and does appear to work better than a very complicated signalization would at this difficult intersection where major arterials and side streets meet adjacent to a major shopping area.